Eerythrocyte (red blood cell) count increases after a while when an individual goes from a low to a high altitude because the the erythrocyte (red blood cell) count increases after a while when an individual goes from a low to a high altitude because the basal metabolic rate is higher at high altitudes temperature is lower at higher altitudes concentration of oxygen and/or total atmospheric pressure is higher at higher altitudes concentration of oxygen and/or total atmospheric pressure is lower at high altitudes